In response to the migrants, U.S. Customs and Border Protection announced that all car traffic lanes at the San Ysidro port of entry had been suspended, as were pedestrian crossings. Mexico also shut off traffic from the U.S.

With military helicopters flying above, U.S. border agents fired tear gas at migrants as some people who tried to break through the border fence.

By the evening, CBP said the San Ysidro port of entry had reopened for cars and pedestrians, and confirmed that multiple illegal entrants were apprehended by Border Patrol agents.

CBP also said that multiple U.S. Border Patrol agents hit by rocks, and in response CBP personnel were “required to deploy crowd dispersing devices, to include pepper ball launching systems, and CS canisters. At this time, there are no injuries reported as a result.”

Homeland Security Secretary Kirstjen Nielsen said DHS will “not tolerate this type of lawlessness.”

“After being prevented from entering the Port of Entry, some of these migrants attempted to breach legacy fence infrastructure along the border and sought to harm CBP personnel by throwing projectiles at them,” Nielsen said in a statement. “As I have continually stated, DHS will not tolerate this type of lawlessness and will not hesitate to shut down ports of entry for security and public safety reasons. We will also seek to prosecute to the fullest extent of the law anyone who destroys federal property, endangers our frontline operators, or violates our nation’s sovereignty.”

Meanwhile, Mexico’s interior department announced it was deporting members of a group of nearly 500 migrants who “violently” attempted to cross the border.

Word of a caravan, predominantly from countries including Honduras, Guatemala, and El Salvador, arose in October. Many of these people are fleeing violence and poverty at home. The caravan became a midterms campaign issue for President Trump and his GOP allies, sounding the alarm bells for a hard line immigration approach to contend with the migrants, some of whom they alleged were criminals.

By last week, more than 5,000 migrants had been camped in and around a sports complex in Tijuana after making their way through Mexico in recent weeks. Many hoped to apply for asylum in the U.S., but agents at the San Ysidro entry point were processing fewer than 100 asylum petitions a day.

Tijuana Mayor Juan Manuel Gastelum declared an international humanitarian crisis for his city by the end of the week, imploring the United Nations to help in the absence of adequate assistance from the Mexican government and his reluctance to allocate his city’s own public resources to counter issues created by the sudden influx of people.

Trump on Thursday threatened to stop immigration and trade flows across the southern border if migrants flood into the U.S. and create an uncontrollable situation.

“If we find that it’s uncontrollable … if we find that it gets to a level where we are going to lose control or people are going to start getting hurt, we will close entry into the country for a period of time until we can get it under control,” Trump told reporters at his Mar-a-Lago resort in Florida on Thanksgiving.

Trump sent thousands of U.S. troops to the border in anticipation of several caravans threatening to cross into the U.S. from Mexico.

Trump has said the U.S. would try to keep people from crossing, but a California judge has blocked that policy for now, after ruling that it goes against the U.S. policy of letting people enter to seek asylum.

The Washington Post reported Saturday that the incoming presidential administration of Andres Manuel Lopez Obrador, who takes office on Dec. 1, had agreed to allow migrants to stay in Mexico as part of a “short-term solution” while the U.S. considered asylum applications.

But Sanchez later denied the report, saying, “There is no agreement of any sort between the incoming Mexican government and the U.S. government.”